Toolhead



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July 22, 1947. R. M'cAcABE i TooL HEAD Filed May 24, 1946 2V Sheets-Sheet 2 A llnmmtor Russen Mfcnae E f E Patented July 22, 1947 Russell McCabe, Detroit, Mich., assigner to The Udylite Corporation, Detroit, Mich., a corporation of Michigan Application May 24, 1946, Serial No. 671,925

to the work for short intervals and withdrawn g therefrom, such as a grinding wheel, a polishing wheel or a bufiing wheel.

The principal object of the invention is to provide a tool head that simulates a carefully controlled manual movement of the tool in the aforementioned operation, in producing the desired pressure of the tool against the work and for the desired duration. The dead weight of the pivotally mounted arm and tool assembly7 carried thereby is usually greater than the desired pressure of the tool against the work. The mere counterbalancing of this weight does not produce a suiciently delicate control and movement of the tool. This diculty is overcome by a yielding and adjustable suspension system capable of totally counterbalancing the tool arm assembly by one adjustment and then producing the desired pressure positively by anoth'er adjustment. These two adjustments involve separate springs operating on the support for the tool arm.

More specifically, this system incorporates two tubes rigidly connected to short levers pivotally attached to the frame of the machine. In each tube is an adjustable spring bearing against a plunger which in turn bears against the frame. The swinging end of the tool arm is suspended from the tubes. T'h'e levers act respectively in opposite directions on the tubes, one upwardly and the other downwardly, on compressing the springs. Consequently, one spring draws the tool arm upwardly against its weight, and the other exerts a positive downward pressure on the arm.

It has been found, however, that the resultant i downward pressure is often too abrupt. Accordingly, another object of the invention is to provide a damping means for this pressure. Th'e construction for this purpose involves a shock absorbing spring acting on the lever that draws the tool arm upwardly. The preferred mechanism embodies an upward extension from the last named lever, with a rod passed through the extension and attached to the frame, and an adjustable spring on the rod and bearing against the extension.

The invention is fully disclosed by way of example in the following description and in the accompanying drawings in which 9 Claims. (Cl. 51--166) Figure 1 is a side elevation of the device, partly in section;

Figure 2 is a section on the line 2--2 of Figure 1;

Figure 3 is a section on the line 3-3 of Figure l;

Figure 4 is a section on the line 4--4 of Figure 3, and

Figure 5 is a section on the line 5-5 of Figure l.

Reference to these views will now be made by use of like characters which are employed to designate corresponding parts throughout.

In Figure i is shown a head or frame member l adapted to be mounted in any suitable manner upon a suitable pedestal or other frame part of a machine. On the member l in turn is fixed another frame part or bracket 2 of U-shape and facing laterally.

In the head i is fixed a horizontal pin 3 eX- tending laterally from both sides of the member I for the purpose of supporting a tool arm. The arm is designated generally by the numeral 4 and is formed at one end with a fork consisting of a pair of circular sides 5 joined by a web 6. The sides 5 are fitted with suitable needle bearings l tted on the exposed ends of the pin 3 to provide a rotatable mounting of the arm on the pin.

The free end of the arm carries a suitable guard or housing 8 in which is mounted a hori- Zontal spindle 9 carrying a' tool I0 such as a grinding wheel, polishing wheel or bufng wheel. A Vertical screw l I is adjustably mounted in the arm 4 near its fulcrum and provides an adjustable downward stop against a shoulder |2 formed on the member I.

A suspension system is mounted on the bracket 2 to determine the pressure of the tool l0 against the work when it is desired that this pressure be greater or less than the weight of the arm 4 and parts carried thereby. This system includes a pair of normally horizontal tubes I3 and I4 pivotally attached to the lower and upper legs I5 and I5 of the bracket by short levers Il and I8v respectively. The levers are rigidly attached to the respective tubes, as by means of welding indicated by the numeral I9.

. Each tube i3 and I4 contains a slidable plunger Z projecting through the end nearer the bracket 2 and engaging the vertical portion or body of the bracket. The opposite end of the plunger is engaged by a coil spring 2| mounted in the tube. The other end of the spring is engaged by a nut 22 vmounted slidably and non-rotatably in the tube by studs 23 extending from the nut into longitudinal slots 24 in the tube.

In the extreme outer end of each tube I3, I4 is fastened a bearing or end plug 25 by suitable means such as studs 26. A screw 21 is passed slidably through each' plug 25 and is threaded through the corresponding nut 22. On the inner side of each end plug 25 the screw carries a spacer 28 fixed thereto by a pin 29. The member '28 thus serves as a back stop which takes the longitudinal pressure of the spring on the screw and prevents the latter from being pushed out through the end plug 25. The exposed outer end of each screw is squared or otherwise shaped at 3o for engagement by a wrench to turn the screw.

A yoke or strap 3| is thrown over both tubes I3, I4 with its open` end lacing downwardly. In the upper end of the yoke 3| is mounted a concave roller 32 supported on a pin 33 and riding upon the upper tube I4.v The sides of the yoke 3| are movable relatively to the upper tube I4 and are secured rigidly to the lower tubey I3 as by means of welding 34.

A double articulation is required between the yoke 3| and the arm 4 as will appear later in the description of operation. A pair of links 35 have their upper ends pivoted to the lower end of the yoke by a pin 36 and their lower ends pivotally connected to the arm 4 by a pin 31. The lower portion of the arm 4 is formed with an ear 38 to permit reversal of the arm and to receive the connecting pin 31 when reversed. The arm is formed with a pair of longitudinal flanges 39 for reinforcement, and these are apertured at 40 to permit assembly of the pin 3l in the position shown.

In adjusting the device, the upper screw 21 is rotated in the direction that advances the corresponding nut 22 and compresses the corresponding spring 2|, thus placing the plunger ZIJ under pressure against the bracket 2. This pressure tends to turn the upper lever I8 on its pivot to raise the yoke 3| and the arm 4. It is preferred that the upper spring be so adjusted until it counterbalances the weight of the arm 4 and parts carried thereby.

It is desired also that the tool Il) engage the work under positive pressure. This pressure is obtained by turning the lower screw 21 to place the corresponding plunger 2!! under pressure against the bracket` 2 in the manner described with reference to the upper plunger. This pressure forces the lower tube I3 downwardly through its attached lever I'I and transmits the downward pressure to the arm 4 through the yoke 3| which is rigidly attached to the lower tube.

The complete counterbalancing of the arm assembly and the application of pressure by separate means result in a floating or damped action of the arm assembly resembling the movement of a polishing or builing wheel applied to the work by hand.

It has been found however that in some cases, especially where the wheel is brought against the work under substantial pressure, the impact of the wheel against the work is too sharp and abrupt. To overcome this diiiiculty, a cushioning means for the pressure-ap-plying movement is provided. Specically, the bracket 2 is extended upwardly in the form of an attached or integral post 4I, and the upper lever I8 is also extended upwardly at I8'.

A tubular stop 42 is held by the extension I8 on a pair of horizontal pins 43. An elongated screw 44 is passed through the stop 42 and has one end hingedly attached at 45 to the extension 4|. A coil spring 46 surrounds the major portion of the screw 44, with one end engaging the stop 42 and the other end engaging a washer 41. The washer is backed by a pair of lock nuts 48 by means of which the` pressure of the spring 46 is adjusted. The pressure of the spring is obviously exerted against the stop 42 in the direction that tends to raise the upper arm I4 and the wheel arm assembly. The spring 45 therefore supplements the spring 2| in the tube I4 and also cushions the pressure of the tool I9 against the work.

Although a specific embodiment of the invention has been illustrated and described, it will be understood that various alterations in` the details of construction may be made without departing from the scope of the invention as indicated by the appended claims.

What I claim is:

1. In a tool head, a frame structure, a tool arm pivotally attached thereto, a downwardly extendimg lever pivotally attached to said structure, a horizontal tube rigidly secured to said lever, a plunger extending through one end of said tube and engaging said structure, a spring in said tube and bearing against said plunger, means for adjusting said spring, and a connection suspended from said tube and pivotally attached to said arm.

2. In a tool head, a frame structure, a tool arm pivotally attached thereto, a downwardly extending lever pivotally attached to said structure, a horizontal tube rigidly secured to said lever, a plunger extending through onev end of said tube and engaging said structure, a spring in said tube and bearing against said plunger,

. means for adjusting said spring, a yoke straddling said tube, a roller in said yoke and riding on said tube, and a pivotal connection between said yoke and said arm.

3. In a tool head, a frame structure, a tool arm pivotally attached thereto, a downwardly extending lever and an upwardly extending lever pivotally attached to said structure, one above the other, horizontal tubes rigidly secured respectively to said levers, a plunger extending through one end of each tube and engaging said structure, a spring in each tube and bearing against the corresponding plunger, means for adjusting said springs, and a connection suspended from the upper tube and rigidly attached to the lower tube and pivotally attached to said arm.

4. In a tool head, a frame structure, a tool arm pivotally attached thereto, a downwardly extending lever and an upwardly extending lever pivotally attached to said structure, one above the other, horizontal tubes rigidly secured respectively to said levers, a plunger extending through one end of each tube and engaging said structure, a spring in each tube and bearing against the corresponding plunger, means for adjusting said springs, a yoke straddling said tubes and rigidly attached to the lower tube, a roller in said yoke and riding on the upper tube, and. a pivotal connection between said yoke and said arm.

5. In a tool head, a frame structure, a tool arm pivotally attached thereto, a downwardly extending lever pivotally attached to said structure, a horizontal tube rigidly secured to said lever, a plunger extending through one end of said tube and engaging said structure, a spring in said tube and bearing against said plunger, a screw mounted rotatably and non-slidably in said tube, a nut on said screw and mounted slidably and nonrotatably in said tube and bearing against said plunger, and a connection suspended from said tube and pivotally attached to said arm.

6. In a tool head, a frame structure, a tool arm pivotally attached thereto, a downwardly extending lever and an upwardly extending lever pivotally attached to said structure, one above the other, horizontal tubes rigidly secured respectively to said levers, a plunger extending through one end of each tube and engaging said structure, a spring in each tube and bearing against the corresponding plunger, a screw mounted rotatably and non-slidably in each tube, a nut on each screw and mounted slidably and non-rotatably in the corresponding tube and bearing against the corresponding spring, and a connection suspended from the upper tube and rigidly attached to the lower tube and pivotally attached to said arm.

7. In a tool head, a frame structure, a tool arm pivotally attached thereto, a lever pivotally attached to said structure and extending downwardly and upwardly therefrom, a horizontal tube rigidly secured to the downwardly extending part of said lever, a plunger extending through one end of said tube and engaging said structure, a spring in said tube and bearing against said plunger, means for adjusting said spring, a connection suspended from said tube and pivotally attached to said arm, a rod slidably mounted in the upwardly extending part of said lever and attached to said structure, a spring on said rod and exerting pressure on said upwardly extending part, and means for adjusting the last named spring.

8. In a tool head, a frame structure, a tool arm pivotally attached thereto, a lever pivotally attached to said structure and extending downwardly and upwardly therefrom, a horizontal tube rigidly secured to the downwardly extending part 0f said lever, a plunger extending through one end of said tube and engaging said structure, a spring in said tube and bearing against Said plunger, means for' adjusting said spring, a connection suspended from said tube and pivotally attached to said arm, a collar having a swivel mounting in said upwardly extending part, a rod slidably mounted in said collar and attached to said structure, a spring on said rod and bearing against a collar, and means for adjusting the last named spring.`

9. In a tool head, a frame structure, a tool arm pivotally attached thereto, a downwardly extending lever and an upwardly extending lever pivotally attached to said structure, one above the other, horizontal tubes rigidly secured respectively to said levers, a plunger extending through one end of each tube and engaging said structure, a spring in each tube and bearing against the corresponding plunger, means for adjusting said springs, a connection suspended from the upper tube and rigidly attached to the lower tube and pivotally attached to said arm, said downwardly extending lever having an upwardly extending part, a rod slidably mounted in said upwardly extending part and attached to said structure, a spring on said rod and exerting pressure on said upwardly extending part, and means for adjusting the last named spring.

RUSSELL MCCABE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,401,659 Pealer June 4, 1946 2,224,652 Kingsbury Dec. 10, 1940 Re. 22,539 Carlson Sept. 5, 1944 FOREIGN PATENTS Number Country Date 493,873 Great Britain Oct. 17, 1938 

